TechTool is pretty good, but I had great success with Disk Warrior. I highly recommend it, even if it means spending another $80. My old beige G3/300 MT now screams. All I did was rebuild the directory of each hard drive partition by starting up from the Disk Warrior CD. I then defraged all the drives while starting up from the CD, too. It worked great. TechTool actually crashed my computer when I tried the same thing with it.